Fast filtering powder catalytic mixtures

ABSTRACT

The catalytic mixture resulting of a metal powder catalyst with a solid material (referred to here as a reaction-aid) that has good filtering properties, does not interfere with the reaction, does not interfere with recycling the catalyst back into the reaction, does not interfere with the refining and recovery of the metal from the catalyst after it is spent, and will not become separated from the catalyst during the preparation of this catalytic mixture, the chemical reaction or the separation of this catalytic mixture from the reaction medium, whereas the ratio of the reaction aid to the catalyst ranges from 0.05 to 20 on a weight basis. A preferred metal powder catalyst is acetylene black supported precious metal. Preferred reaction aids are sibunit powder or activated carbon. The catalytic mixture can be used for the catalytic transformation of compounds, such as the hydrogenation of olefins, or the hydrogenation of nitro compounds.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is US national stage of internationalapplication PCT/EP2007/060942, which had an international filing date ofOct. 15, 2007, and which was published in English under PCT Article21(2) on Apr. 23, 2009.

The invention of this patent concerns itself with a fast filteringpowder catalytic mixture that it highly effective for chemical reactionson the basis of the amount of its catalytic metal. This inventioninvolves forming a mixture of the metal powder catalyst with a solidmaterial (referred to here as the reaction aid) that has excellentfiltering properties, does not interfere with the reaction, does notinterfere with recycling the catalyst back into the reaction, does notinterfere with the refining and recovery of the metal from the catalystafter it is spent, and will not become separated from the catalystduring the preparation of this catalytic mixture, the chemical reactionor the separation of the catalytic mixture from the reaction medium.

Powder metal catalysts are used for a large number of hydrogenation,dehydrogenation, isomerization, reductive amination, reductivealkylation, oxidation, hydration and other reactions of compounds. Thesepowdered metal catalysts are prepared by supporting small metal crystalsonto a powder support such as activated carbon, carbon black, acetyleneblack, silica, alumina, magnesia, silica-alumina, ceria, zeolites,hydrothalcites, mixed metal oxides and other powder supports. The carbonsupports have been found to be the most useful for use with the presentinvention and they may come from one or more sources such as, but notlimited to, wood, peat, coal, saw dust, carbon containing wastematerials (e.g., wood palates, agricultural waste material, plasticwaste materials, polymer waste materials and others), rice husks,coconut shells, bones, lignite, petroleum based residues and sugars.Commercially available carbons which may be used in this inventioninclude, but are not limited to, Barneby & Sutcliffe™, Darco™, Nuchar™,Columbia JXN™, Columbia LCK™, Calgon PCB™, Calcon BPL™, Westvaco™,Norit™, CECA™ and Barnaby Cheny NB™. The present invention is especiallyeffective when used together with carbon blacks.

Carbon black is elemental carbon in a very fine particulate form that ismore amorphous than graphite. It consists of planes of carbon atomsfused randomly together to form spherical particles that adhere to eachother to create chainlike aggregates which in turn form agglomerates.The spherical particles range from ˜10 to 500 nm and the averageaggregate diameters range from 100 to 800 nm. The typical classes ofcarbon black are characterized by the size distribution of the sphericalparticles, the degree of aggregation, degree of agglomeration, the typesof surface moieties and the method of production. The two main types ofcarbon black are produced by either the incomplete combustion methodwhere the carbon source is oxidized in a limited amount of oxygen or thethermal decomposition method in the absence of oxygen (vide-infra). Thefurnace blacks are made via the incomplete combustion method and theymay contain up to 15 wt % oxygen and acetylene black is made by thethermal decomposition method and is relatively oxygen free. Furnaceblacks have surface areas ranging from 100 to 1500 m2/g and the surfaceareas of acetylene blacks range from 60 to 300 m2/g. These macro porousmaterials are generally believed to have “flat-surfaces” with relativelyvery few meso and micro pores. Furnace blacks are typically produced byburning natural gas and liquid aromatics in a furnace with a limited andcontrolled amount of oxygen at about ˜1400° C. The ensuing cracking andpolymerization of the hydrocarbons followed by their dehydrogenationlead to the formation of turbostratic carbon particles. Immediatelyafter the reaction zone, the carbon black is quenched to 200-250° C.with a water spray to impede its further reaction with oxidizing gasessuch as steam and CO₂. Nonetheless, some oxidation does occur during thequenching step and this creates additional surface oxide groups.Acetylene black is produced in the absence of oxygen via thermaldecomposition at very high temperatures (>2500° C.) and its surface israther devoid of surface oxide groups. Thus the adsorptive properties ofacetylene black are determined by its olefinic character (i.e., theratio of its pi-to-sigma bonds). Carbon blacks conduct electricalcharges and this may also play a strong role in their use as a catalystsupport. Carbon blacks are also very compressible and the level ofcompression not only changes the physical aspects of the support, but italso effects the chemical properties such as electrical conductivity andthe influence this can have on the metal crystallites supported on thecarbon black where the catalysis occurs. The table below describes someof the typical carbon blacks one can use with this invention and theirsources.

TABLE 1 Typical carbon blacks and their sources. Carbon Black ChemicalParticle Type Process Diameter, nm Feedstock Lamp Black Incomplete 50-100 Coal Tar Combustion Hydrocarbons Channel Incomplete 10-30Natural Gas Black Combustion Furnace Incomplete 10-80 Natural Gas/ BlackCombustion Liquid Aromatic Thermal Thermal 150-500 Natural Gas BlackDecomposition Acetylene Thermal 35-70 Acetylene Black Decomposition

These catalysts are typically prepared by suspending the powder supportin a solution, adding one or more precious metal compounds to the liquidsuspension with the support, fixing the metal onto the support andoptionally reducing the fixed metal. The fixing agent may be addedbefore the metal, with the metal, after the metal, during the wholeprocess and/or combinations thereof. The fixed metal may also beoxidized before reduction, after reduction or be oxidized instead ofbeing reduced. Another possible high temperature treatment could be inthe presence of an inert gas such as nitrogen and this could be appliedin various sequences and temperatures in combination with the otherpreparation steps mentioned above. Other gases (CO, CO₂, and others) andvaporized compounds (e.g., organic compounds and others) could be usedas well in order to achieve the various desired effects. The suspensionliquid may be aqueous, it may be organic or it could be composed of manyphases and the properties of the suspension and/or its phases can befurther changed at various preparation steps to modify the resultingcatalyst. One such property could be the pH of the suspension at varioussteps of the catalyst preparation, where the addition of various bases(KOH, NaOH, Na2CO3, NaHCO3 and others) and/or acids (HCl, HNO3, H2SO4and others) to a liquid suspension of the support before, after and/orduring the various preparation steps can greatly impact the propertiesand performance of the catalyst. In the case the catalyst contains morethan one metal the acid and/or base can be added before, after, duringand/or in the solution containing one or more metals before addition. Inthe case that the different metals or metal combinations are added atdifferent times during the various preparation steps of the catalyst,one could add the acid and/or base before, after, during and/or in thesolution containing one or more metals for each of these metaladditions. For further details about pH effects on catalyst preparationwith aqueous phases please see F. P. Daly, W. M. Jensen and D. J.Ostgard, in Catalysis of Organic Reactions, edited by M. G. Scaros andM. L. Prunier, vol. 62 (1995) p 13-21. The catalyst could be made of onemetal or more than one metal. In the case that the catalyst is made ofmore than one metal, all the metals could be added at once or variouscombinations of metals could be added during the various steps of thecatalyst's preparation. The metal compounds could be salts, organiccomplexes, combinations thereof and others as well. The metal and/or itscompound may dissolve during the preparation of the catalyst and/or themetal compound may change in-situ during preparation to produce thedesired catalyst. Other suitable catalyst preparation methods for thisinvention include but are not limited to the use of metal evaporation,the incipient wetness spray impregnation of the various solutions usedin preparing the catalyst, the wet spray impregnation of the varioussolutions used in preparing the catalyst, dipping the catalyst powder invarious liquids and other methods as well. All commercially availablepowder metal catalysts can be used with the invention of this patent.

The metals used in the preparation of these catalysts can be one or moreprecious metals, one or more base metals, one or more alkali andalkaline metals, one or more rare earth metals or combinations of metalsfrom one or more of these groups. This invention of this patent may alsobe used with Raney-type catalysts that are made by leaching out most ofthe Al from an alloy of Al with one or more metals that contain at leastone catalytic metal and potentially modifying metals that can functionas promoters, inhibitors or co-catalysts. After leaching, this activatedmetal powder catalyst may or may not be washed to various degrees beforeit is applied to the present invention.

Metal powder catalysts are typically used with liquid suspensions intank reactors, where eventually the catalyst must be separated from thereaction mixture by sedimentation, filtration and/or other suitablemethods. Other reactor types such loop reactors, cascade reactors, tubereactors and others may also take advantage of the present invention andthe reaction in question may be performed batch wise, continuous,semi-continuous or by any other process method. The catalytic reactionmay also involve a gas phase of one or more gases (e.g., H₂ forhydrogenation, O₂ for oxidation and N₂ may be used as an inert diluent)that needs to diffuse through the liquid phase to reach the solidsurface of the catalyst before it can adsorb, be activated (e.g., viadissociation of H₂ or O₂) and participate in the reaction. The gasreactant may be added to the compound being transformed or it may justsimply facilitate the reaction. Unfortunately some of the propertiesthat make a catalyst very active, such as a very small support particlesize and unique morphology, may also make it very difficult to filterafter the reaction is performed. Hence the goal of this invention is tomaintain and increase, if possible, the effectiveness of the metal inthe chemical reaction while improving the filterability of the catalyst.Catalyst filtration can be performed with various screens, sinteredmetal discs, candle filters (e.g., Dr. M filters), membrane filters,Schenk filters, Rosemond filters and other devices for the separation ofsolids from liquids with or without the use of gas pressure toaccelerate this separation. These methods as well as others may be usedin combination with the present invention for the improved efficiency ofa chemical transformation with a metal powder catalyst by allowing oneto keep the best powder metal catalyst properties for the reaction whileenhancing its ability to be separated from the reaction mixture at theparticular time it needs to be so that the reaction can proceed smoothlyand the catalyst can be easily recycled back into the system over itsexpected lifetime.

The present invention involves forming a mixture of the metal powdercatalyst with a solid material (referred to here as a reaction aid) thathas excellent filtering properties, does not interfere with thereaction, does not interfere with recycling the catalyst back into thereaction, does not interfere with the refining and recovery of the metalfrom the catalyst after it is spent, and will not become separated fromthe catalyst during the preparation of this catalytic mixture, thechemical reaction or the separation of the catalyst mixture from thereaction medium. This mixture can range from 0.05 part of reaction aidto 1 part of catalyst on a weight basis to a combination of 20 parts ofreaction aid to 1 part of catalyst on a weight basis. The optimalcombinations of reaction aid to catalyst on a weight basis range from 12to 1 down to 0.5 to 1 on a weight basis. The weight ratio of reactionaid to catalyst of 5 to 1 was found to be the best for the reactionsperformed here.

One of the most effective materials used here was found to be a powderform of sibunit from the Institute of Hydrocarbons Processing (IHP) ofthe Siberian Branch of the Russian Academy of Science. Sibunit is athree dimensional matrix porous carbonaceous material that is describedin U.S. Pat. No. 4,978,649, which is hereby incorporated by referenceherein in its entirety. Of note are the three dimensional matrixcarbonaceous materials which are obtained by introducing gaseous orvaporous carbon-containing compounds (e.g., hydrocarbons) into a mass ofgranules of carbonaceous material (e.g., carbon black); decomposing thecarbon-containing compounds to deposit carbon on the surface of thegranules; and treating the resulting material with an activator gascomprising usually of steam to provide a porous carbonaceous material inthe form of a hollow body that has taken the shape of the originalgranule carbon material. This material can be ground to a course powderthat has a surface area about ˜410 m2/g and a pore volume ˜0.6 cm3/g(for the pores smaller than 1500 angstroms) with ˜95% of the particlesbeing between 5 and 400 microns. Of course, other sibunit materials withdifferent particle sizes, pore volumes and surface areas can be alsoused with the present invention. The sibunit powders with particle sizedistribution D₅₀ values (the value where half of the particles aregreater or lower than this value) between 1000 μm and 5 μm areespecially effective as reaction aids.

Other reaction aids that were found to be very effective are activatedcarbons. The preferred activated carbons were steam activated and/orphosphoric acid activated and had particle size distribution (PSD) D₅₀values ranging from 1000 μm to 5 μm. Other activated carbons withdifferent PSD D₅₀ values that were activated by other methods can alsobe used in the current invention.

The reaction aid may not be the best support for the catalyst inquestion and its function is to assist in the removal of the catalystfrom the reaction suspension. In the best case, the reaction aid mayalso provide additional absorptive properties for the removal ofcatalyst poisons from the reaction mixture as the reaction proceeds.Another benefit is that it will facilitate the removal of heat duringexothermic reactions by the collisions of its particles with thecatalyst particles in the reaction mixture.

The reaction aid can also be specially designed to fulfill its role inthe reaction medium. Specially designed activated carbons and othermaterials or the use of those most appropriate commercially availableactivated carbons and other materials for the functions of a reactionaid that meet all the above mention requirements insomuch as thecatalyst remains mixed with the reaction aid during catalystpreparation, the reaction, separation of the catalytic mixture from thereaction medium and the refining of the spent catalyst for metalrecovery to where none of these processes are interfered with by thereaction aid itself. During metal recovery, the activated carbon orsibunit that was used as a reaction aid can be burnt along with thespent catalyst to yield an ash rich in the catalytic metal that can befurther processed. In inorganic catalytic support systems, the reactionaid will have to be as soluble as the support in the acid solution orwhatever solution is used to dissolve the catalyst before the metal isrecovered.

Sibunit powder is very effective as a reaction aid, in that it remainshomogeneously mixed with the catalyst during catalyst preparation, thereaction, separation of the catalytic mixture from the reaction mediumand the refining of the spent catalyst for metal recovery to where noneof these processes are interfered with by sibunit itself. The sibunitpowder can also be burnt with the spent catalyst resulting in a rapidrecovery of the catalytic metal. Additional benefits of the sibunitpowder is its graphitic-like conductive structure that seems topractically agglomerate with catalysts on conductive supportsimpregnated with metals such as the Pd+Pt+Fe on acetylene blackcatalysts used for the hydrogenation of aromatic nitro groups (e.g.,aniline and dinitrotoluene) and the curved shape of these particles thatresulted from the crushing of sibunit's original graphitic carbon hollowstructures (vide-supra) which provides preferred channels in thecatalyst filter cake for the reaction medium to flow through. Anotherbenefit is that it is easier to remove more water from the catalyst inthe presence of sibunit than with the catalyst alone. This will resultin lower water contents meaning that one can send lower product weightswhen shipping the catalyst. The lower water content will also benefitcatalysts that are more active in their oxidic states (e.g., the abovementioned Pd+Pt+Fe catalyst used for the hydrogenation of aromatic nitrogroups) in that air can keep the catalytic metal oxidic withoutreduction by the support (i.e, activated carbons and other supports maybe reducing agents for metals). Actually the properties of sibunit allowone to adjust the wetness of the catalytic mixture with far fewerdifficulties than with the catalyst by itself, thereby improving theflexibility of this system for optimal product design and production.

The reaction aid can be added to the catalyst during any, many and/orall of the catalyst preparation steps during this procedure and this isusually, but not always, done during the last step where the catalystpreparation slurry in being homogenized by stirring before it isfiltered. Another possibility would be to prepare the catalyst as it isnormally done, the catalyst is then separated from the preparationslurry (via normal methods such as but not limited to sedimentation,filtration and centrifugation), the catalyst could then be optionallywashed, the catalyst is then re-suspended into a slurry, the reactionaid is added to this new slurry and after it has been homogenized bystirring the new catalyst mixture is then filtered. Another possibilitywould be to mix the catalyst with the reaction aid in a fluidized bed ofeither a reactive or inert gas. In principle, any method that provides auniform mixture between the catalyst and the reaction aid can be used toproduce the invention of this patent.

One method of particular interest involves preparing the catalyst as itis normally done, allow the catalyst to settle to the bottom of thesuspension's vessel after the last washing step, draw off theover-standing solution, add fresh water, add the reaction aid, stir tohomogeneity and separate it from the liquid phase by a suitable methodsuch as filtration, decantation, centrifugation, combinations of methodsand other suitable means as well. One could also wash the freshly mixedcatalytic mixture by allowing it to settle to the bottom of the vessel,drawing off the over-standing water, adding fresh water, stirring tohomogeneity and repeat as necessary before the final catalytic mixtureis separated from its last wash suspension. Instead of decantation, onecould also use other suitable solid-liquid separation techniques, suchas but not limited to, filtration, centrifugation and combinations ofmany methods for the washing of the catalyst and reaction aid mixture.

This mixture of the above mentioned reaction aid and catalyst can beused for a large range of organic transformations including, but notlimited to, hydrogenation, dehydrogenation, isomerization, reductiveamination, reductive alkylation, oxidation, hydration and otherreactions. The moieties that can be transformed include but are notlimited to: olefinic groups, acetylenic groups, nitro groups,hydroxylamines, oximes, enamines, nitrates, nitrile groups, aromaticrings, heterocyclic aromatic rings, carbonyl compounds (e.g., aldehydesand ketones), carboxylic acids, carboxlate salts, acid chlorides, iminegroups, imides, esters, amides and others. The 2 main examples describedhere are the hydrogenation of olefinic groups such as the hydrogenationof cinnamic acid to the saturated acid and the hydrogenation of nitrogroups such as with the reduction of dinitrotoluene to toluene diamine.

The hydrogenation of olefins on metal catalysts such as precious metalcatalysts proceeds rapidly and the preferred support type may not be thebest for filtration. Not only that, the dilution of these very activecatalysts with the above mentioned reaction aids allows the reaction toprogress with far fewer mass transfer limitations and the reaction'soverall exotherm is considerably more controllable.

The catalytic hydrogenation of nitro groups with metal catalysts is avery demanding reaction due to the high hydrogen demand (3 hydrogenmolecules per nitro group) and the very exothermic nature of thisreaction. There are many types of nitro-compound hydrogenationsperformed in industry. One of the more commercially interesting andtechnically challenging is the hydrogenation of dinitrotoluene (DNT) totoluenediamine (TDA). This hydrogenation is performed with preciousmetal powder catalysts at temperatures ranging from room temperature to200° C. and pressures ranging from atmospheric pressure to 200 bar. Thepreferred reaction conditions are within the ranges of 50° to 130° C.and 3 to 12 bar. This reaction can be performed in an excess of hydrogenor under a stoichiometric amount of hydrogen.

As mentioned earlier, the hydrogenation of DNT is a very exothermic andhydrogen demanding reaction that is further complicated by thisreactant's strong adsorption onto the catalyst. Hence, it is easy tohave a hydrogen deficient surface during this reaction and this usuallyleads to enhanced metal leaching and rapid catalyst deactivation due tocoke formation. FIG. 1 displays the DNT hydrogenation scheme. The DNThydrogenation data over a Pd/C catalyst from Neri et al. (please see,Neri, M. G. Musolino, S. Galvagno, Ind. Eng. Chem. Res., 34 (1995)2226-2231) has shown that this reaction can take 3 or more parallelroutes. The 2,4-DNT can be hydrogenated through an intermediate4-hydroxyamino-2-nitrotoluene (4HA2NT) before it is converted to4-amino-2-nitrotoluene (4A2NT) and eventually TDA. It is possible that4HA2NT goes directly to TDA without forming 4A2NT. The 2,4-DNT can alsodirectly form 4A2NT and then TDA without generating 2HA4NT at all.

The last route forms the 2-amino-4-nitrotoluene (2A4NT) intermediatethat proceeds further to TDA. Interestingly,2-hydroxyamino-4-nitrotoluene (2HA4NT) has not been found in any of thereaction mixtures and due to the explosive nature of hydroxylamines, the4HA2NT should always be avoided. Regardless of the route, all of theabove mentioned intermediates are very active and adsorb strongly. Thus,these intermediates and DNT can all readily yield undesired sideproducts such as tars (e.g., dimers), light boilers (e.g., ringhydrogenated products and toluidines), products with water (e.g.,methylaminocyclohexenones) and others (e.g., N-allyl-diamino toluenes)if the catalytic surface is hydrogen deficient. This can be avoided bysuspending the catalyst in a hydrogen rich TDA/water mixture having thesame TDA-to-water ratio as the stoichiometric product mixture producedby this hydrogenation and only pumping in enough DNT so that it isimmediately hydrogenated to completion (please see U.S. Pat. No.2,619,503) at ˜6.9 bars and between 90 and 110° C. This is typically howthis reaction is performed on a commercial scale, however this may notbe the best testing method on a lab scale since the activity of thecatalyst is dependent on the pump speed and the lifetime of the catalystcould last for days. Another laboratory testing method would be to pulsethe DNT into the hydrogen rich stoichiometric TDA/water mixture(vide-supra) so that there would be only a very slight DNT access over avery limited period of time. In this way, one could measure the activityof the catalyst as a function of how much TDA per kg of precious metalthat has been formed to give a catalyst deactivation profile. Based onthis information, it was decided to use the above mentioned pulse testprocedure at 10 bars and 120° C. for the hydrogenation of DNT overcatalysts of the present invention to determine their effectiveness forthis reaction.

This precious metal catalyst supported on carbonaceous materials hasbeen optimized over the years (please see: U.S. Pat. Nos. 2,823,235,3,127,356, and J. R. Kosak, in Catalysis of Organic Reactions, edited beR. E. Malz Jr., (1968) 31-41) and the best support was found to beacetylene black due to its highly olefinic nature. Palladium wasinitially chosen as the main catalytic metal due to its high activityand relatively low cost. This was improved by promoting it with a smallamount of platinum, however this catalyst was too active and yieldedunwanted side products via reactions like ring hydrogenation. Theselectivity of this catalyst was then corrected by the addition of ironoxide that impeded the undesired reactions. Iron has also been proven tobe a promoter for the hydrogenation of aliphatic nitro compounds [pleasesee: E. Auer, M. Berweiler, M. Gross, J. Pietsch, D. J. Ostgard, P.Panster, in Catalysis of Organic Reactions, edited by M. E. Ford, vol.82 (2001)293-300] as well as for nitro-aromatics, where it wasadditionally useful for avoiding ring hydrogenation. One of thecatalysts from this optimization work has a 0.75 wt. % Pd+0.083 wt. %Pt+0.853 wt. % Fe metal combination supported on acetylene black thatnot only exhibited high activity, but also high selectivity. Thiscatalyst was made by precipitating 4.5 wt. % Pd+0.5 wt. % Pt+5 wt. % Feonto the acetylene black support followed by the dilution of thecatalyst with fresh acetylene black at the ratio of 5 parts of acetyleneblack to 1 part of the 4.5 wt. % Pd+0.5 wt. % Pt+5 wt. % Fe on acetyleneblack catalyst to result in the overall metal loading of 0.75 wt. %Pd+0.083 wt. % Pt+0.853 wt. % Fe. While acetylene black is the bestsupport for the highest hydrogenation rate, its above mentioned physicaland chemical properties make if very difficult to separate from thereaction mixture by filtration or any other method even if one mixesfresh acetylene black at a ratio of 5-to-1 with the catalyst. Hence thechoice to use an acetylene black supported catalyst means that onefavors a fast and selective hydrogenation over fast filtration.

Activated carbon supported catalysts have also been found to be usefulfor the hydrogenation of DNT to TDA [please see, Neri, M. G. Musolino,S. Galvagno, Ind. Eng. Chem. Res., 34 (1995) 2226-2231] and while theactivated carbon supported catalysts filter much faster than theacetylene black supported ones, these catalysts are far less active andless selective. Activated carbons have far more meso and micro poresthan acetylene black. If the metal crystals deposit in these smallerpores, the resulting activated carbon supported catalyst will have moreproblems with mass transfer limitations into and out of the pores and inthis case, the hydrogenation rate can quickly become dependent on thediffusion rate of hydrogen into these smaller pores for these metalcrystals. Not only does that make the metal crystals in these pores lessactive, they are also more likely to form tars due to the strongadsorption strength of DNT under hydrogen deficient conditions resultingin faster deactivation rates and lower reaction selectivity. Theresulting TDA and potential side products can also readsorb on othermetal crystals as they diffuse out of the carbon's pore system and thatwill increase the chances of even more secondary reactions leading toeven lower reaction selectivity. Moreover, activated carbons are notconductive and they cannot take advantage of this mild metal-to-supportinteraction between the active site on the catalytic metal and theelectronic structure of the support, as is the case with acetyleneblack. Hence the choice to use an activated carbon supported catalystmeans that one favors a fast filtration over faster hydrogenation ratesand better product selectivity.

Thus the choice of catalyst determines the bottleneck of the process andit wasn't until the present invention that one could have high activitywith high selectivity and fast filtration. The catalyst systems thatworked the best for the hydrogenation of DNT were the differentacetylene black supported 4.5 wt. % Pd+0.5 wt. % Pt+5 wt. % Fe catalyststhat were diluted 5-to-1 with the sibunit powder. It was also found tobe rather useful to wash the catalyst before it was mixed with thereaction aid.

Another preferred embodiment of this invention was the 5-to-1 dilutionof an 4.5 wt. % Pd+0.5 wt. % Pt+5 wt. % Fe on acetylene black catalystwith a steam activated carbon made from wood and comprising of needleshaped particles that pack to form catalyst beds with preferred channelsfor the liquid reaction medium to flow through. Other activated carbonsfrom other sources, carbons activated by different methods, carbonsactivated by more than one method and carbons that are not evenactivated at all along with carbons having different morphologies canalso be preferred reaction aids if they fulfill the reaction aidrequirements described in this patent.

The hydrogenation of nitro-compounds can take place in the vapor,slurry, trickle, aerosol and/or liquid phase. The reaction could beperformed as a batch process or it could be performed as a continuousprocess. The continuous processes may involve, but they are not limitedto, a type of circulation process. This invention also includes acontinuous process where the nitro-compound is added at a rate that isthe same or slower than the rate of hydrogenation, so that theconcentration of the nitro-compound is kept to a very low level. Thefeeding rate of the nitro-compound may be so low that the level of thenitro-compound is 1000 ppm or lower. Of course, this reaction can beperformed at a controlled excess of DNT by balancing the rate of DNTaddition to catalyst's hydrogenation rate. This invention also includesthe use of the previously mentioned catalyst of this invention in acontinuous process that utilizes a second hydrogenation reactor (ormore) to hydrogenate any nitro-compounds and/or intermediates that wereremaining from the hydrogenation in the first hydrogenation reactor.

The nitro-compound hydrogenation of this invention may take place in thepresence of the neat nitro-compound, at high concentrations of thereactant, at very low concentrations of the reactant and/or in thepresence of the product mixture that would be acting like a solvent.This hydrogenation may also take place in the presence of practicallyonly the desired amine or under lower water contents than what isstoichiometrically produced if the water is removed by a satisfactorymethod (e.g., distillation) during the reaction. The nitro-compoundhydrogenation of this invention may take place in the presence of asolvent. The reactor type could be, but is not limited to, a stirredtank reactor, a continuous stirred tank reactor, a loop reactor or atube reactor. This nitro-compound hydrogenation may occur betweenatmospheric pressure and 200 bars of hydrogen and the temperature canrange from ˜10° C. to 210° C.

This invention encompasses the preparation and the use of a catalyticmixture comprising of a reactive and selective catalyst along with areaction aid for the effective (on a metal basis) catalytictransformation of compounds into their products followed by the rapidseparation of this mixture from the reaction medium as facilitated bythe reaction aid. The reaction aid has to have good filtrationproperties, does not interfere with the reaction, does not interferewith recycling the catalyst back into the reaction, does not interferewith the refining and recovery of the metal from the catalyst after itis spent, and will not become separated from the catalyst during thepreparation of this catalytic mixture, the chemical reaction, separationof the catalytic mixture from the reaction medium and during therefining and recovery of metal from the spent catalytic mixture. Thisinvention also includes the above mentioned catalytic mixture as acomposition of matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: FIG. 1 illustrates the hydrogenation of DNT to TDA.

FIG. 2: FIG. 2 illustrates an apparatus used to determine thefilterability of catalysts, supports, reaction aids and mixturesthereof.

FIG. 3: FIG. 3 is a graph showing DNT pulse hydrogenation data forvarious catalyst compositions.

APPLICATION EXAMPLE 1

The pulse hydrogenation of dinitrotoluene (DNT) to toluenediamine (TDA).

DNT is typically hydrogenated in an industrial setting via a continuousmode, where the DNT feed rate is slow enough to keep its concentrationlow enough so that it doesn't poison the catalyst or become a safetyhazard. This means that the hydrogenation rate will be dependent on theDNT feed rate. The goal of our pulse hydrogenation method was to keepthe DNT concentration low enough so that it would be comparable to theindustrial setting while measuring the activity of the catalyst. We wereable to do so by pulsing in the DNT feed at a rate that was slightlyfaster than the rate of hydrogenation so that we could measure catalystactivity while keeping the time of the slight excess of DNT to aminimum.

The pulse hydrogenation method was started by placing enough catalyst inthe reactor so that exactly 3 milligrams of precious metal sum total arepresent along with 101 grams of TDA and 59 grams of water (thereaction's stoichiometric TDA-to-water ratio) in the 500 ml autoclave.The autoclave was then closed, purged with nitrogen 3 times, purged 3times with hydrogen and heated to the reaction temperature of 120° C.over a period of 20 minutes while the reactor was stirring at 300 rpmand kept under 5 bar hydrogen. Once the autoclave reached 120° C., thehydrogen pressure was adjusted to 10 bar hydrogen and the stirring ratewas increased to 1700 rpm. The reaction was then started by pulsing 4milliliters of molten DNT into the reactor over 30 seconds with an HPLCpump. The HPLC pump head, the DNT reservoir and all the stainless tubingused for the transport of DNT was kept at 95° C. to keep the DNT molten.A Büchi hydrogen press flow controller (bpc 9901) was used to monitorthe hydrogen consumption and once the reaction stopped to consumehydrogen, another pulse of DNT was introduced at the same feed rate.This procedure was continued up to a maximum of 45 pulses had beenintroduced. The data from these hydrogenations can be seen in FIG. 3 andin data tables 4 to 14.

APPLICATION EXAMPLE 2

The batch hydrogenation of cinnamic acid.

The low pressure hydrogenation of cinnamic acid was carried out over 200milligrams of catalyst slurried into 40 ml of ethanol and added to 80 mlof a 0.844 M cinnamic acid ethanolic solution at 25° C. and atmosphericpressure in a baffled glass reactor outfitted with a hallow shaft bubbleinducing stirrer. The reaction began as the stirrer was started and spunat 2000 rpm during the reaction. The total hydrogenation uptake betweenthe third and eighth minutes of the reaction was divided by 5 and thendivided by 200 to calculate the cinnamic acid activity value in units ofml of hydrogen per minute per mg of catalyst. The cinnamic acidhydrogenation activity was also calculated on the mg of precious metalbasis to facilitate the comparison of the different catalysts. Theresults of these hydrogenations are listed in table 1.

TABLE 2 The cinnamic acid hydrogenation data. Cinnamic Acid CinnamicAcid Activity Activity ml H₂/min/ ml H₂/min/mg Catalyst mg catalystprecious metal Comparative Example 3 67 8043 Comparative Example 4 2224440 Comparative Example 6 196 3920 Comparative Example 8 34 1700Example 1 86 10324 Example 2 96 11525 Example 4 76 9124

APPLICATION EXAMPLE 3

Determining the Filterability of the Catalyst

The apparatus in FIG. 2 is used for determining the filterability of thecatalyst. The lid of this apparatus has a t-tube outfitted with an inletfor a pressurized gas (e.g., nitrogen or air) and a monometer so thatthe pressure can be monitored and controlled. The lid can be attachedand tightened onto the main vessel with a hand-wheel and a locking nut,and this is made airtight by the use of a viton-o-ring gasket. The mainvessel consists of a jacketed container (a stainless steel cylinder)that can be connected in an airtight fashion with the help of aviton-o-ring to an intermediate ring (or cylinder) that goes overanother viton-o-ring, a filter cloth, a perforated plate and finally thedraining funnel that can be locked into place with a hand-wheel and alocking nut. At the bottom of the draining funnel is a drainage tubethat is directed to an empty beaker. Before carrying out each test, ablank run is performed with 400 ml of deionised water to check if thefilter cloth is free of support materials, reaction aids and catalystparticles from the previous tests. The blank test is performed byplacing a stopper in the drainage tube coming from the draining funnel,400 ml of deionised water is poured into the jacketed container, thefiltration unit is then closed by putting on the lid and tightening it,the plug is then removed from the drainage tube, the device ispressurized with a gas from the T-tube on the lid to exactly 1 bar andthe stopwatch is started simultaneously. The time it takes for all ofthe water to be pressed out is measured in seconds and the stopwatch isstopped after all the liquid is pushed out and at the appearance of thefirst gas bubbles. If the blank test is quicker than 4 seconds, then thefilter cloth is still O.K. If not, the filter cloth will have to bereplaced. The test is performed by placing a stopper in the drainagetube followed by suspending 10 grams of the catalyst, support, reactionaid or mixtures thereof into 390 ml of deionised water. Any agglomeratesthat are present should be broken up by swirling the beaker of thesuspension. The suspension is then stirred 15 seconds with a Krups 3 mix4004 high speed mixing rod on level 3 before it is immediately pouredinto the filtration unit and the beaker is then rinsed out into thefiltration unit with 10 ml of deionised water. In a very quick fashion,The lid is tightened in place, the stopper is removed from the drainagetube, the gas pressured is adjusted to exactly 1 bar and the stopwatchin simultaneously started. The time runs until all of the water comesout of the drainage tube and the first gas bubbles appear. After themeasurement the filtration apparatus is taken apart and cleanedthoroughly with water. The filter cloth can be cleaned by forcing waterback up the drainage tube and through the filter cloth before the nextblank run is performed. Each catalyst, support, reaction aid or mixturethereof is measured 3 times and the average values of these tests arelisted in table 3 for the above mentioned materials measured here.

TABLE 3 The filterability of the catalysts, supports, reaction aids andmixtures thereof. Filtration Time, in minutes Catalyst or Support (m)and seconds (s) Comparative Example 1 5 m 15 s Comparative Example 2 0 m41 s Comparative Example 3 4 m 30 s Comparative Example 4 >8 mComparative Example 5 4 m 28 s Comparative Example 6 >8 m ComparativeExample 8 0 m 35 s Example 1 2 m 03 s Example 2 2 m 15 s Example 3 2 m24 s Example 5 2 m 41 s Example 6 3 m 08 s Example 9 3 m 72 s Example 102 m 18 s Example 11 0 m 38 s

COMPARATIVE EXAMPLE 1

A commercially available 50% compressed acetylene black used as asupport for the catalysts in this patent contained less than 1 wt. %water and had a filtration time of 5 minutes and 15 seconds (please seeApplication example 3 and table 3).

COMPARATIVE EXAMPLE 2

A sibunit powder (vide-supra) with 95% of its particles between 5 and400 microns, a BET surface area of ˜410 m²/gram and a pore volume of 0.6cm³/gram (for the pores smaller than 1500 angstroms) was used as asupport and a reaction aid for the catalysts in this patent. Thismaterial contained less than 1 wt. % water and had the filtration timeof 0 minutes and 41 seconds (please see Application example 3 and table3).

COMPARATIVE EXAMPLE 3

One part of a commercially available 4.5 wt. % Pd+0.5 wt. % Pt+5.0 wt. %Fe on a 50% compressed acetylene black catalyst made by Degussa'sproprietary technology was mixed with 5 parts of a fresh 50% compressedacetylene black on a weight basis in an aqueous suspension, stirred tohomogeneity, and filtered. The resulting mixture had the final metalloading of 0.75 wt. % Pd+0.083 wt. % Pt+0.83 wt. % Fe, contained 74.2wt. % water and had a filtration time of 4 minutes and 30 seconds(please see Application example 3). This catalytic mixture had acinnamic acid hydrogenation activity of 8043 ml H₂ per minute permilligram of precious metal (please see application example 2) and itwas also tested for the pulse hydrogenation of DNT to TDA as accordingto application example 1. The results for the DNT hydrogenation test canbe seen in table 4 and FIG. 3. The maximum DNT hydrogenation activityduring this test was 429 ml H₂/min/mg of precious metal and the finalactivity was 236 ml H₂/min/mg of precious metal at the yield of 39.9 MTof TDA per kg of precious metal resulting in a deactivation rate of 45%over this range.

TABLE 4 The dinitrotoluene hydrogenation data for comparative example 3.Hydrogenation Activity in Metric Tons TDA yielded per ml H₂ per minuteper milligram kilogram of precious metal of precious metal 0.6 235 1.3277 2.1 316 3.1 400 4.1 400 5.2 429 6.3 420 7.4 427 8.6 424 9.7 402 10.8417 11.9 407 13.0 383 14.1 393 15.2 374 16.4 369 17.5 359 18.6 351 19.7320 20.8 341 22.0 343 23.1 332 24.2 326 25.4 315 26.5 310 27.6 300 28.7283 29.8 290 30.9 270 32.1 271 33.2 266 34.3 263 35.4 255 36.5 266 37.7246 38.8 244 39.9 236

COMPARATIVE EXAMPLE 4

A commercially available 4.5 wt. % Pd+0.5 wt. % Pt+5.0 wt. % Fe on a 50%compressed acetylene black catalyst made by Degussa's proprietarytechnology contained 81.1 wt. % water and had a filtration time longerthan 8 minutes (please see Application example 3). This catalyst had acinnamic acid hydrogenation activity of 4440 ml H₂ per min per milligramof precious metal (please see application example 2) and it was alsotested for the pulse hydrogenation of DNT to TDA as according toapplication example 1. The results for the DNT hydrogenation test can beseen in table 5 and FIG. 3. The maximum DNT hydrogenation activityduring this test was 367 ml H₂/min/mg of precious metal and the finalactivity was 219 ml H₂/min/mg of precious metal at the yield of 40 MT ofTDA per kg of precious metal resulting in a deactivation rate of 40.3%over this range.

TABLE 5 The dinitrotoluene hydrogenation data for comparative example 4.Hydrogenation Activity in Metric Tons TDA yielded per ml H₂ per minuteper milligram kilogram of precious metal of precious metal 0.7 207 1.4238 2.1 294 3.2 320 4.3 347 5.4 367 6.5 354 7.6 336 8.7 365 9.9 356 11.0348 12.1 338 13.2 360 14.4 343 15.5 336 16.6 321 17.7 332 18.8 330 20.0332 21.1 314 22.2 298 23.3 289 24.4 290 25.5 288 26.7 281 27.7 270 28.9278 30.0 264 31.1 253 32.2 258 33.3 254 34.4 239 35.5 252 36.6 233 37.8237 38.9 219 40.0 219

COMPARATIVE EXAMPLE 5

One part of a commercially available 4.5 wt. % Pd+0.5 wt. % Pt+5.0 wt. %Fe on a 50% compressed acetylene black catalyst made by Degussa'sproprietary technology was mixed with 5 parts of a fresh 50% compressedacetylene black on a weight basis in an aqueous suspension, stirred tohomogeneity, and filtered. The resulting mixture had the final metalloading of 0.75 wt. % Pd+0.083 wt. % Pt+0.83 wt. % Fe, contained 77.8wt. % water and had a filtration time of 4 minutes and 28 seconds(please see Application example 3).

COMPARATIVE EXAMPLE 6

A commercially available 4.5 wt. % Pd+0.5 wt. % Pt+5.0 wt. % Fe on a100% compressed acetylene black catalyst made by Degussa's proprietarytechnology contained 78 wt. % water and had a filtration time longerthan 8 minutes (please see Application example 3). This catalyst had acinnamic hydrogenation activity of 3920 ml H₂ per min per milligram ofprecious metal (please see application example 2).

COMPARATIVE EXAMPLE 7

A commercially available 4 wt. % Pd+1.0 wt. % Pt+1.0 wt. % Fe on anactivated carbon catalyst made by Degussa's proprietary technology wastested for the pulse hydrogenation of DNT to TDA as according toapplication example 1. The results for the DNT hydrogenation test can beseen in table 6 and FIG. 3. The maximum DNT hydrogenation activityduring this test was 216 ml H₂/min/mg of precious metal and the finalactivity was 173 ml H₂/min/mg of precious metal at the yield of 24.28 MTof TDA per kg of precious metal resulting in a deactivation rate of19.9% over this range.

TABLE 6 The dinitrotoluene hydrogenation data for comparative example 7.Hydrogenation Activity in Metric Tons TDA yielded per ml H₂ per minuteper milligram kilogram of precious metal of precious metal 0.56 158 1.20167 1.87 174 2.50 204 3.21 209 3.90 199 4.61 198 5.37 191 6.01 203 6.72216 7.39 207 8.09 216 8.82 209 9.53 212 10.25 203 10.96 213 11.69 20012.38 207 13.09 207 13.79 196 14.48 190 15.21 193 15.94 188 16.61 19717.33 194 18.00 188 18.62 186 19.33 182 20.04 187 20.75 192 21.47 19022.14 182 22.85 177 23.56 185 24.28 173

COMPARATIVE EXAMPLE 8

A commercially available catalyst consisting of 1.8 wt. % Pd+0.2 wt. %Pt+2.0 wt. % Fe on sibunit powder (this powder sibunit is described incomparative example 2) that was made by Degussa's proprietary technologycontained 27.3 wt. % water and had a filtration time of 0 minutes and 35seconds (please see Application example 3). This catalyst had a cinnamicacid hydrogenation activity of 1700 ml H₂ per min per milligram ofprecious metal (please see application example 2) and it was also testedfor the pulse hydrogenation of DNT to TDA as according to applicationexample 1. The activity results for the DNT hydrogenation test were solow that they could not be reliably measured and the experiment had tobe stopped quite early after its start so as to avoid the unsafe buildup of nitro bodies in the reaction medium. One can safely assume thatthis catalyst is relatively inactive for the hydrogenation of DNT.

EXAMPLE 1

One part of a commercially available 4.5 wt. % Pd+0.5 wt. % Pt+5.0 wt. %Fe on a 50% compressed acetylene black catalyst made by Degussa'sproprietary technology was washed very well with deionised water andafter washing, it was mixed with 5 parts of sibunit powder (this sibunitpowder was described in comparative example 2) on a weight basis in anaqueous suspension, stirred to homogeneity, and filtered. The resultingmixture had the final metal loading of 0.75 wt. % Pd+0.083 wt. % Pt+0.83wt. % Fe, contained 0.9 wt. % water and had a filtration time of 2minutes and 03 seconds (please see Application example 3). Thiscatalytic mixture had a cinnamic acid hydrogenation activity of 10324 mlH₂ per min per milligram of precious metal (please see applicationexample 2) and it was also tested for the pulse hydrogenation of DNT toTDA as according to application example 1. The results for the DNThydrogenation test can be seen in table 7 and FIG. 3. The maximum DNThydrogenation activity during this test was 632 ml H₂/min/mg of preciousmetal and the final activity was 510 ml H₂/min/mg of precious metal atthe yield of 40.1 MT of TDA per kg of precious metal resulting in adeactivation rate of 19.3% over this range.

TABLE 7 The dinitrotoluene hydrogenation data for example 1.Hydrogenation Activity in Metric Tons TDA yielded per ml H₂ per minuteper milligram kilogram of precious metal of precious metal 0.8 397 1.7406 2.7 420 3.8 511 4.8 490 6.0 500 7.1 556 8.3 554 9.5 576 10.7 56311.9 547 13.1 567 14.3 603 15.5 574 16.7 600 17.9 563 19.0 602 20.2 63221.4 602 22.5 632 23.7 612 24.9 576 26.0 622 27.2 592 28.4 548 29.6 62830.8 574 31.9 559 33.1 583 34.3 552 35.5 613 36.6 565 37.8 507 39.0 57840.1 510

EXAMPLE 2

During the last steps of the preparation of a 4.5 wt. % Pd+0.5 wt. %Pt+5.0 wt. % Fe catalyst on a 100% compressed acetylene black made byDegussa's proprietary technology, sibunit powder (this sibunit powderwas described in comparative example 2) was added to the aqueoussuspension of the catalyst in the ratio of 5 parts sibunit powder to 1part catalyst on a weight basis. This mixture was stirred tohomogeneity, filtered and then washed with deionised water. Theresulting catalytic mixture had the final metal loading of 0.75 wt. %Pd+0.083 wt. % Pt+0.83 wt. % Fe, contained 29.7 wt. % water and had afiltration time of 2 minutes and 15 seconds (please see Applicationexample 3). This catalytic mixture had a cinnamic acid hydrogenationactivity of 11525 ml H₂ per minute per milligram of precious metal(please see application example 2) and it was also tested for the pulsehydrogenation of DNT to TDA as according to application example 1. Theresults for the DNT hydrogenation test can be seen in table 8 and FIG.3. The maximum DNT hydrogenation activity during this test was 418 mlH₂/min/mg of precious metal and the final activity was 297 ml H₂/min/mgof precious metal at the yield of 39.9 MT of TDA per kg of preciousmetal resulting in a deactivation rate of 28.9% over this range.

TABLE 8 The dinitrotoluene hydrogenation data for example 2.Hydrogenation Activity in Metric Tons TDA yielded per ml H₂ per minuteper milligram kilogram of precious metal of precious metal 0.79 212 0.82289 1.72 314 2.48 327 3.33 358 4.17 373 4.69 368 5.78 365 6.90 357 7.68398 9.92 396 11.04 383 12.22 392 13.37 418 14.55 409 15.67 407 16.85 40017.97 407 19.12 411 20.27 385 21.45 365 22.60 387 23.75 374 24.93 36726.08 368 27.22 350 28.40 354 29.55 341 30.61 319 31.76 318 32.91 33934.06 329 35.24 327 36.42 308 37.57 300 38.72 294 39.90 297

EXAMPLE 3

During the last steps of the preparation of a 4.5 wt. % Pd+0.5 wt. %Pt+5.0 wt. % Fe catalyst on a 100% compressed acetylene black made byDegussa's proprietary technology, sibunit powder (this sibunit powderwas described in comparative example 2) was added in the ratio of 5parts sibunit powder to 1 part catalyst on a weight basis to an aqueoussuspension of the catalyst. This mixture was stirred to homogeneity,filtered and then washed with deionised water. The resulting catalyticmixture had the final metal loading of 0.75 wt. % Pd+0.083 wt. % Pt+0.83wt. % Fe, contained 35.7 wt. % water and had a filtration time of 2minutes and 24 seconds (please see Application example 3). Thiscatalytic mixture was also tested for the pulse hydrogenation of DNT toTDA as according to application example 1. The results for the DNThydrogenation test can be seen in table 9 and FIG. 3. The maximum DNThydrogenation activity during this test was 407 ml H₂/min/mg of preciousmetal and the final activity was 295 ml H₂/min/mg of precious metal atthe yield of 38.7 MT of TDA per kg of precious metal resulting in adeactivation rate of 27.5% over this range.

TABLE 9 The dinitrotoluene hydrogenation data for example 3.Hydrogenation Activity in Metric Tons TDA yielded per ml H₂ per minuteper milligram kilogram of precious metal of precious metal 1.1 340 2.1321 3.2 348 4.3 341 5.4 359 6.5 361 7.6 365 8.7 370 9.7 357 10.9 37811.9 368 13.0 352 14.2 365 15.2 407 16.3 395 17.5 376 18.6 395 19.7 38120.8 404 21.9 387 23.1 375 24.2 375 25.3 402 26.4 393 27.5 385 28.6 35029.8 371 30.9 354 32.0 356 33.1 335 34.2 317 35.3 336 36.5 316 37.6 30738.7 295

EXAMPLE 4

One part of a commercially available 4.5 wt. % Pd+0.5 wt. % Pt+5.0 wt. %Fe on a 50% compressed acetylene black catalyst made by Degussa'sproprietary technology was diluted with 5 parts of sibunit powder (thissibunit powder was described in comparative example 2) on a weight basisin an aqueous suspension that was stirred to homogeneity and filtered.The resulting mixture had the final metal loading of 0.75 wt. % Pd+0.083wt. % Pt+0.83 wt. % Fe and had a cinnamic acid hydrogenation activity of9124 ml H₂ per min per milligram of precious metal (please seeapplication example 2). This catalyst was also tested for the pulsehydrogenation of DNT to TDA as according to application example 1. Theresults for the DNT hydrogenation test can be seen in table 10 and FIG.3. The maximum DNT hydrogenation activity during this test was 487 mlH₂/min/mg of precious metal and the final activity was 327 ml H₂/min/mgof precious metal at the yield of 38.99 MT of TDA per kg of preciousmetal resulting in a deactivation rate of 32.9% over this range.

TABLE 10 The dinitrotoluene hydrogenation data for example 4.Hydrogenation Activity in Metric Tons TDA yielded per ml H₂ per minuteper milligram kilogram of precious metal of precious metal 0.45 234 0.48300 1.18 327 1.94 360 2.84 383 3.69 409 4.60 448 5.75 446 6.93 444 7.99455 10.16 473 11.34 433 12.52 487 13.73 437 14.91 463 16.09 468 17.30469 18.51 461 19.69 454 20.84 416 22.02 427 23.14 426 24.35 404 25.47389 26.62 420 27.74 367 28.31 353 28.98 344 29.83 340 30.95 359 32.13370 33.27 354 34.42 364 35.57 347 36.72 333 37.90 332 38.99 327

EXAMPLE 5

During the last steps of the preparation of a 4.5 wt. % Pd+0.5 wt. %Pt+5.0 wt. % Fe catalyst on a 50% compressed acetylene black made byDegussa's proprietary technology, an activated carbon (steamed activatedand based on wood—this is the first type of such a support used here)was added to an aqueous suspension of the catalyst in the ratio of 5parts activated carbon to 1 part catalyst on a weight basis. Thismixture was stirred to homogeneity, filtered and then washed withdeionised water. The resulting catalytic mixture had the final metalloading of 0.75 wt. % Pd+0.083 wt. % Pt+0.83 wt. % Fe, contained 13.1wt. % water and had a filtration time of 2 minutes and 41 seconds(please see Application example 3).

EXAMPLE 6

During the last steps of the preparation of a 4.5 wt. % Pd+0.5 wt. %Pt+5.0 wt. % Fe catalyst on a 50% compressed acetylene black made byDegussa's proprietary technology, activated carbon (steam activated andbased on wood—this is the second type of such a support used here) wasadded to an aqueous suspension of the catalyst in the ratio of 5 partsactivated carbon to 1 part catalyst on a weight basis. This catalyticmixture was stirred to homogeneity, filtered and then washed withdeionised water. The resulting mixture had the final metal loading of0.75 wt. % Pd+0.083 wt. % Pt+0.83 wt. % Fe, contained 31.1 wt. % waterand had a filtration time of 3 minutes and 08 seconds (please seeApplication example 3). This catalytic mixture was tested for the pulsehydrogenation of DNT to TDA as according to application example 1. Theresults for the DNT hydrogenation test can be seen in table 11 and FIG.3. The maximum DNT hydrogenation activity during this test was 483 mlH₂/min/mg of precious metal and the final activity was 303 ml H₂/min/mgof precious metal at the yield of 38.8 MT of TDA per kg of preciousmetal resulting in a deactivation rate of 37.3% over this range.

TABLE 11 The dinitrotoluene hydrogenation data for example 6.Hydrogenation Activity in Metric Tons TDA yielded per ml H₂ per minuteper milligram kilogram of precious metal of precious metal 0.9 275 1.7312 2.5 364 3.5 396 4.1 362 5.1 417 6.1 430 7.0 400 7.6 381 8.9 413 9.9467 11.0 483 12.0 449 13.2 447 14.0 412 15.1 483 16.2 483 17.3 433 18.3432 19.3 426 19.9 409 20.9 395 22.0 409 22.9 349 24.0 398 24.9 328 25.9354 27.0 349 28.0 332 29.1 343 30.2 350 31.2 346 32.3 335 33.4 335 34.5321 35.5 302 36.7 309 37.8 302 38.8 303

EXAMPLE 7

During the last steps of the preparation of a 4.5 wt. % Pd+0.5 wt. %Pt+5.0 wt. % Fe catalyst on a 50% compressed acetylene black made byDegussa's proprietary technology, activated carbon (steam activated andbased on wood—this is the second type of such a support used here) wasadded to an aqueous suspension of the catalyst in the ratio of 5 partsactivated carbon to 1 part catalyst on a weight basis. This mixture wasstirred to homogeneity, filtered and then washed with deionised water.The resulting catalytic mixture had the final metal loading of 0.75 wt.% Pd+0.083 wt. % Pt+0.83 wt. % Fe, contained 66 wt. % water and wastested for the pulse hydrogenation of DNT to TDA as according toapplication example 1. The results for the DNT hydrogenation test can beseen in table 12 and FIG. 3. The maximum DNT hydrogenation activityduring this test was 497 ml H₂/min/mg of precious metal and the finalactivity was 319 ml H₂/min/mg of precious metal at the yield of ˜39.3 MTof TDA per kg of precious metal resulting in a deactivation rate of37.3% over this range.

TABLE 12 The dinitrotoluene hydrogenation data for example 7.Hydrogenation Activity in Metric Tons TDA yielded per ml H₂ per minuteper milligram kilogram of precious metal of precious metal 1.1 442 2.0376 2.9 392 4.0 437 5.1 424 6.2 396 7.3 453 8.4 436 9.6 477 10.7 45311.8 460 13.0 497 14.1 443 15.2 486 16.4 477 17.5 465 18.7 462 19.8 46821.0 463 22.1 458 23.3 465 24.4 465 25.6 455 26.7 440 27.9 422 29.0 45430.2 433 31.3 431 32.5 409 33.6 409 34.7 402 35.9 367 37.0 370 38.2 34139.3 319

EXAMPLE 8

During the last steps of the preparation of a 4.5 wt. % Pd+0.5 wt. %Pt+5.0 wt. % Fe catalyst on a 100% compressed acetylene black made byDegussa's proprietary technology, sibunit powder (this sibunit powderwas described in comparative example 2) was added to an aqueoussuspension of the catalyst in the ratio of 5 parts sibunit powder to 1part catalyst on a weight basis. This mixture was stirred tohomogeneity, filtered and then washed with deionised water. Theresulting catalytic mixture had the final metal loading of 0.75 wt. %Pd+0.083 wt. % Pt+0.83 wt. % Fe and it was tested for the pulsehydrogenation of DNT to TDA as according to application example 1. Theresults for the DNT hydrogenation test can be seen in table 13 and FIG.3. The maximum DNT hydrogenation activity during this test was 439 mlH₂/min/mg of precious metal and the final activity was 312 ml H₂/min/mgof precious metal at the yield of 37.1 MT of TDA per kg of preciousmetal resulting in a deactivation rate of 28.9% over this range.

TABLE 13 The dinitrotoluene hydrogenation data for example 8.Hydrogenation Activity in Metric Tons TDA yielded per ml H₂ per minuteper milligram kilogram of precious metal of precious metal 0.7 274 1.4302 1.9 279 2.8 347 3.7 411 4.7 388 5.8 402 6.9 398 8.0 407 9.1 435 10.2419 11.3 419 12.4 439 13.6 409 14.7 407 15.9 416 17.0 404 18.1 416 19.2416 20.4 404 21.5 413 22.7 378 23.8 366 24.9 372 26.0 373 27.0 346 28.0365 29.1 348 30.2 350 31.4 336 32.5 340 33.6 341 34.8 333 35.9 335 37.1312

EXAMPLE 9

During the last steps of the preparation of a 4.5 wt. % Pd+0.5 wt. %Pt+5.0 wt. % Fe catalyst on a 100% compressed acetylene black made byDegussa's proprietary technology, sibunit powder (this sibunit powderwas described in comparative example 2) was added to an aqueoussuspension of the catalyst in the ratio of 5 parts sibunit powder to 1part catalyst on a weight basis. This catalytic mixture was stirred tohomogeneity, filtered and then washed with deionised water. Theresulting mixture had the final metal loading of 0.75 wt. % Pd+0.083 wt.% Pt+0.83 wt. % Fe, contained 49.3 wt. % water and had a filtration timeof 3 minutes and 43 seconds (please see Application example 3).

EXAMPLE 10

During the last steps of the preparation of a 4.5 wt. % Pd+0.5 wt. %Pt+5.0 wt. % Fe catalyst on a 100% compressed acetylene black made byDegussa's proprietary technology, activated carbon (steam activated andbased on wood—this is the second type of such a support used here) wasadded to an aqueous suspension of the catalyst in the ratio of 5 partsactivated carbon to 1 part catalyst on a weight basis. This catalyticmixture was stirred to homogeneity, filtered and then washed withdeionised water. The resulting mixture had the final metal loading of0.75 wt. % Pd+0.083 wt. % Pt+0.83 wt. % Fe, contained 64.6 wt. % waterand had a filtration time of 2 minutes and 18 seconds (please seeApplication example 3).

EXAMPLE 11

During the last steps of the preparation of a 4.5 wt. % Pd+0.5 wt. %Pt+5.0 wt. % Fe catalyst on an steam activated wood based carbon(type 1) made by Degussa's proprietary technology, sibunit powder (thissibunit powder was described in comparative example 2) was added to anaqueous suspension of the catalyst in the ratio of 5 parts sibunitpowder to 1 part catalyst on a weight basis. This catalytic mixture wasstirred to homogeneity, filtered and then washed with deionised water.The resulting mixture had the final metal loading of 0.75 wt. % Pd+0.083wt. % Pt+0.83 wt. % Fe, contained 3.0 wt. % water and had a filtrationtime of 0 minutes and 38 seconds (please see Application example 3).

Table 14 summarizes the data measured on the catalysts, supports,reaction aids and catalytic mixtures described here. One can see thatthe addition of a reaction aid not only improves the filterability ofthe catalyst system, but is also improves the activity of the catalystson a active metal basis. In any case, neither the activity nor theselectivity of the catalyst is made worse by the addition of thereaction aid. Another advantage was that one could more readily controlthe final amount of water in the catalyst from either very high levelsof ˜80 wt. % to practically 0 wt. % depending of the desired propertiesof the catalyst.

TABLE 14 The summary of the catalyst data Rxn Cat. to wt. % CA DNT maxDNT fina1 Final % Deact. Filter Time Cat¹ Sup.² Add³ Add. Ratio⁴ H₂OAct.⁵ Act.⁶ act.⁷ TDA Yield⁸ DNT test⁹ in m & s¹⁰ CE1 AB 50% — — <1 — —— — — 5 m 15 s CE2 Sib — — <1 — — — — — 0 m 41 s CE3 AB 50% — 1:5 AB 50%74 8043 429 236 39.9 45  4 m 39 s CE4 AB 50% — — 81 4440 367 219 40 40.3 >8 m CE5 AB 50% — 1:5 AB 50% 78 — — — — — 4 m 28 s CE6 AB 100% — —78 3920 — — — — >8 m CE7 AC — — — — 216 173 24  19.9 — CE8 Sib — — 271700 Activity was too low to measure 0 m 35 s E1 AB 50% Sib 1:5  110324  632 510 40  19.3 2 m 03 s E2 AB 100% Sib 1:5 30 11525  418 29739.9 28.9 2 m 15 s E3 AB 100% Sib 1:5 36 — 407 295 38.7 27.5 2 m 24 s E4AB 50% Sib 1:5 58 9124 487 327 39  32.9 — E5 AB 50% 1-AC¹¹ 1:5 13 — — —— — 2 m 41 s E6 AB 50% 2-AC¹² 1:5 31 — 483 303 38.8 37.3 3 m 08 s E7 AB50% 2-AC 1:5 66 — 497 319 39.3 39.3 — E8 AB 100% Sib 1:5 — — 439 31237.1 28.9 — E9 AB 100% Sib 1:5 49 — — — — — 3 m 43 s E10 AB 100% 2-AC1:5 65 — — — — — 2 m 18 s E11 1-AC Sib 1:5 30 — — — — — 0 m 38 s¹Catalyst designation in patent: CE = comparative example and E =example. ²Sup. = Support type: AB = Acetylene Black with % compression,AC = activated carbon (with type number) and Sib = sibunit powder.³Reaction aid: AC = activated carbon (with type number) and Sib =sibunit powder. ⁴The catalyst to additive ratio on a weight basis, wherethe additive is either fresh support or a reaction aid. ⁵The cinnamicacid hydrogenation activity in ml H₂/min/milligram of precious metal.⁶The maximum activity of the DNT pulse hydrogenation test in the unitsof ml H₂/min/mg precious metal. ⁷The final activity of the DNT pulsehydrogenation test in the units of ml H₂/min/mg precious metal. ⁸Thefinal TDA yield during the DNT test in units of MT TDA/kg preciousmetal. ⁹The % of deactivation during the DNT pulse hydrogenation test tothe final yield. ¹⁰The filtration time as determined by the filtrationtest in minutes (m) and seconds (s). ¹¹1-AC = Activated carbon type 1.¹²1-AC = Activated carbon type 2.

The DNT hydrogenation results (see application example 1) aregraphically demonstrated in FIG. 3.

While modifications may be made by those skilled in the art, suchmodifications are encompassed within the spirit of the present inventionas defined by these disclosures and claims.

The invention claimed is:
 1. A catalytic mixture comprising: a) a metal powder catalyst comprising metal crystals that have been fixed to a powder support by a fixing agent; and b) a reaction aid which aids in filtering but does not interfere with a reaction, which comprises particles with a particle size distribution, D₅₀, of 5 μm-1000 μm and which is selected from the group consisting of a sibunit powder and an activated carbon; wherein the ratio of said reaction aid to said catalyst is 0.05-20 on a weight basis.
 2. The catalytic mixture of claim 1, wherein the ratio of reaction aid to catalyst is from 4 to 6 on a weight basis.
 3. The catalytic mixture of claim 1, wherein the ratio of reaction aid to catalyst is 5 on a weight basis.
 4. The catalytic mixture of claim 1, comprising an acetylene black supported precious metal catalyst and sibunit powder, wherein the ratio of sibunit powder to catalyst is from 0.05 to 20 on a weight basis.
 5. The catalytic mixture of claim 4, wherein the ratio of sibunit powder to catalyst is 5 on a weight basis.
 6. The catalytic mixture of claim 1, comprising an acetylene black supported precious metal catalyst and activated carbon, wherein the ratio of said activated carbon to catalyst is from 0.3 to 20 on a weight basis.
 7. The catalytic mixture of claim 6, wherein the ratio of activated carbon to catalyst is from 4.0 to 6.0 on a weight basis.
 8. The catalytic mixture of claim 7, wherein the ratio of activated carbon to catalyst is 5 on a weight basis.
 9. The catalytic mixture of claim 1, comprising an activated carbon derived from one or more sources selected from the group consisting of wood, peat, coal, saw dust, carbon containing waste materials, rice husks, coconut shells, bones, lignite, petroleum based residues and sugars.
 10. The catalytic mixture of claim 9, further comprising a metal selected from the group consisting of: Pt or Fe.
 11. The catalytic mixture of claim 9, further comprising Pd.
 12. The catalytic mixture of claim 11, further comprising acetylene black.
 13. In a chemical reaction in which an organic compound or a nitrate undergoes a hydrogenation, dehydrogenation, isomerization, reductive amination, reductive alkylation, oxidation and/or hydration, the improvement comprising catalyzing said reaction with the catalytic mixture of claim
 1. 14. The improvement of claim 13, wherein said chemical reaction is the hydrogenation of an olefin.
 15. The improvement of claim 13, wherein said chemical reaction is the hydrogenation of a nitro compound.
 16. The improvement of claim 13, wherein said chemical reaction is the hydrogenation of an aromatic nitro compound.
 17. The improvement of claim 13, wherein said chemical reaction is the hydrogenation of dinitrotoluene to toluenediamine.
 18. The improvement of claim 17, wherein said catalytic mixture comprises a precious metal powder catalyst containing Pd, Pt and Fe.
 19. The improvement of claim 18, wherein said Pd, Pt and Fe are present in said precious metal powder catalyst at the weight ratios of 9:1:10 for Pd:Pt:Fe.
 20. The improvement of claim 19, wherein the reaction aid in said catalytic mixture comprises sibunit powder. 